Cyanide salts are commonly used in the jewellery industry but are not commonly available by the general population in retail markets. Gold-stripping process involves the use of potassium cyanide, hydrogen peroxide (35%) and water. The gold is stripped and made brighter in appearance (1% gold is lost during the stripping process). Almost every company in the gold-manufacturing community, especially in small- and medium-sized operations, uses this process.
Geller and Alsop1
reported three lethal cases of acute cyanide poisoning by ingestion of a metal polish cleaner solution containing cyanide salts. The patients belonged to a community who had liberal access to cyanide salts. Hydroxocobalamin was not available.
Reports describing suicide attempts through ingestion of cyanide usually do not report the range of supposed ingested dose. Nevertheless, it has been reported that the ingestion of 50–100 mg of cyanide salt is followed by almost instantaneous collapse and cessation of respiration.2
Initial clinical manifestations of acute cyanide poisoning are non-specific. A blood-lactate concentration of greater than or equal to 8 mmol/l is a relatively sensitive marker of cyanide poisoning, defined as a blood-cyanide concentration greater than or equal to 39 μmol/l.3
The presence of lactic acidosis and arteriolisation of venous blood gases may serve as an early clue to the diagnosis of cyanide poisoning.4
In fact, there is a general consensus that emergent care of the patient should be based on the clinical presentation rather than on blood-cyanide concentrations.3
On arrival to the emergency department, our patient presented with deep metabolic acidosis with high anion gap, a blood lactate concentration more than double the level observed in severe intoxications and a venous blood oxygen saturation of 100%. Therefore, though information regarding blood-cyanide levels was not available, the suspicion of severe acute cyanide poisoning was high. Afterwards, it was confirmed by the patient himself.
Hydroxocobalamin is a haeme-like molecule with a complexed cobalt atom. Each hydroxocobalamin molecule binds 1 cyanide ion to form non-toxic cyanobobalamin. It is well tolerated, with no known major toxicities in doses up to 10 g administered to healthy volunteers.5
Borron et al6
reported a survival rate of 71% in a group of 14 patients diagnosed for acute cyanide poisoning and treated with hydroxocobalamin. In this study, 4 of the 12 patients who ingested a cyanide salt were in cardiac or respiratory arrest and received hydroxocobalamin 0.5–4 h after ingestion. Unfortunately, three of them died.
We report on a case of severe acute cyanide poisoning by ingestion successfully treated with hydroxocobalamin, regardless of the delay of approximately 4.5 h between ingestion and administration. Although we believe supportive care only could have been enough to save our patient, hydroxocobalamin treatment clearly hastened his clinical improvement ().
The limitations of this case report are both the absence of blood cyanide concentrations determination and the measurement of the quantity of cyanocobalamin eliminated in urine.
- Acute cyanide poisoning requires a high index of suspicion for diagnosis in a patient with unexplained severe lactic acidosis. Physicians should be aware that cyanide is generally available to members of the jewellery industry community, a fact which should be considered while treating those suspected of attempting suicide by consuming cyanide.
- Hydroxocobalamin is a safe and highly effective therapy for acute cyanide poisoning by ingestion. Moreover, this case report supports the existence of a window of time for antidote administration.